Acoustical enclosure to simulate



Aug- 7, 1962 H. H. SANTI Re. 25,217

AcousTICAL ENCLOSURE To SIMULATE ORGAN TUNES @riginal Filed April 25? 1955 Herr/J b. Jaz/7 INVENTOR.

United States 4Patent Utilice Re. 25,21' Reissued Aug. 7, 1961 25 217 ACOUSTICAL ENCLSURE T() SIMULATE ORGAN TUNES Harris H. Santi, La Porte, Tex., assignor to Rototone, Inc., a corporation of Texas Original No. 2,847,081, dated Aug. 12, 1958, Ser. No.

503,609, Apr. 25, 1955. Application for reissue Aug.

19, 1959, Ser. No.Y 73,153

9 Claims. (Cl. 181-31) Matter enclosed in heavy brackets I2] appears in the original patent but forms no part of this reissue specilication; matter printed in italics indicates the additions made by reissue.

This invention relates -bro-adly Vto sound reproduction apparatus and, more particularly, to a speaker enclosure as a part -of `such `apparatus which enables the reproduction ot" improved acoustical values.

Various enclosures have been devised for improving the tone quality of sound wavesl emanating fro-rn the speaker, and particularly the quality of bass notes. or low frequency sound waves. lnasmuch as such notes do not travel :in free air, an early development in this field was the infinite type baffle in which the back of the speaker cone was sealed oft within an enclosure so as to enable the cone vibrations to drive pressurized air and thereby provide greater tone sensitivity.

However, the infinite type baffle provided little ilexibility for sound waves of differing frequencies, and a later development introduced the bass reflex in which the back of the speaker was loaded by means of a valved or choked enclosure.

Of the commercially available speaker enclosures of which l am aware, the best alleged performance is the reproduction of sound waves down to 30y cycles. However, it is `admitted that this is accomplished only with a l decibel loss. Furthermore, this. particular enclosure is dependen-t for its operation upon building acousticsi.e., it embodies a triangular construction for use in the corner of a room.

An object of the present invention is to provide a speaker enclosure capable of producing improved tone values independently of building acoustics.

Another object is to provide a speaker enclosure which enables the reproduction `of bass tones not possible with prior enclosures and,'more particularly the full bass range of a pipe organ without power loss.

A further object is to provide a-speaker enclosure constructed in a novel manner to provide a considerably longer path `of sound Waves between opposite sides of the speaker cone than has been possible with prior enclosures of comparable size.

Still another object is to provide -a speaker enclosure in which `a stereophonic effect may 4be simulatedwith the use of a single speaker.

It has heretofore been proposed to simulate the reverberation effect of organ music by what is known as a tremulant which comprised a rotatable blade posi- -tioned within the speaker cone or `a `channel or duct within a speaker enclosure. The result has been a baffling of the sound waves and a consequent variation of intensity.

An object of this invention is to provide a speaker enclosure in which "a truer' pipe organ effect may be obtained and, more particularly, in which such sound may be simulated without bafliing.

Other objects, advantages and features of this invention will be apparent to one skilled in the 'art upon a consideration of the written specification, the attached claims and the annexed drawings.

In the drawings, wherein like reference characters are used throughout to designate like par-ts:

FIG. 1 is a vertical sectional view of an illustrative embodiment of the acoustical enclosure of the prese] invention mounted or standing in a preferred positie with respect -to the floor or other support;

FIG, 2 is another vertical sectional view of the e1 closure but taken substantially along broken line 2 2 l FIG. l; and

FIG. 3 is a horizontal sectional view of the upp chamber of the enclosure taken substantially along broke line `3 3 of FIG. l.

According to one of its novel aspects, the speaker e closure of the present invention [cludes] includes a char ber on the front side of the speaker cone which lengthe the travel of sound waves between the front and back the cone, and thus improves the tone quality, as previous mentioned. ln addition, lthis upper chamber is provid with outlet openings through opposite sides thereof sur that the sound emanating from the speaker may be spre: rather than being directed to the audience, thus produc: a stereophonic elect with Konly ya single speaker. Si further, the upper chamber of the speaker enclosui while not actually choking the sound waves emanati from the speaker, does provide a certain load-ing effe upon the front of the speaker cone which further i1 proves the speaker sensitivity.

According to another of :its novel concepts, this speak enclosure is provided with a passageway above the porti thereof for receiving the speaker cone which is ct structed to elongate the pattern of sound waves emanati from the speaker cone and thereby reproduce the f bass range of a pipe organes previously mentions More particularly, the enclosure is provided with mea for receiving Ithe speaker cone suspended Within a 10u chamber in which the back of the cone may be loade and the aforementioned passageway is disposed in s1 r rounding relation to the speaker cone receiving means its lower end from which it is convergent toward upper end so as to atten out or elongate the patte of sound waves. i v

Preferably, the Iaforementioned novel aspects of t present invention are combined into an enclosure co: prising a cabinet partitioned off into upper and lou chambers and being closed except for an outlet from 1 upper chamber and an inlet to the lower chamber. 'I outlet from Ithe upper chamber comprises the afo mentioned openings through opposite side walls of t enclosure, and the `store-mentioned passageway opens i1 the upper chamber with its lower end surrounding opening through the partition which-provides the afo mentioned speaker `cone receiving means. Further, inlet to the lower chamber comprises a choke of a s so as to permit substantially no free air -on the bz side of the speaker co-ne and, as shown, is substantie axially aligned with the speaker cone receiving openi In accordance with a still `further novel aspect of t invention, and particularly for use in the reproduction organ music, -a blade similar to the trernulant rotors p viously ymentioned may be mounted in the upper cham of the enclosure for rot-ation above the speaker cone ceiving means and about an axis which extends longitt nally of side walls for the enclosure through which ou openings are provided. Thus, the blade is operative divert sound waves emana-ting from the speaker from t opening to the other. However, with the lblade rotata mounted above fthe opening provided for receiving speaker cone, there is no mufing of the sound waves. the preferred embodiment of the invention, the abo described rotatable blade construction is combined v the sound wave pattern elongating passageway.

Referring now to a detailed description of the drawir the speaker enclosure shown therein is designated in entirety by the numeral 10 and comprises a cabinet hav and bottom walls 111 and 12, respectively, as well as )osite side walls =13 and 14. In this respect, the terms p, bottom and side, as well as corresponding ns, such as upper and lower, are merely relative l do not necessarily define the position of the enclosure h respect to its support, such as the floor 15. That is, rough the upright position of the enclosure shown in 3S. l and 2, in which bottom wall 12 is adjacent the r 15, is preferred, the enclosure may be disposed in er positions, as will -be described hereinafter. The walls of the enclosure may be made of any suitable ustical material, such as the laminated plywood which ndicated in the cross sectional views of the drawings. s walls are joined to one another in a secure manner is to prevent excessive vibration within the enclosure further, to provide an air-tight interior for the inet. `he cabinet is divided Iby a partition 16- extending subltially transversely between the side walls thereof into ipper chamber 17 and a lower chamber 18. An inlet he lower chamber comprises a choke 19 through the :om wall 112 and an outlet from the upper chamber lprises openings 20 through opposite side walls 13 of cabinet. The cabinet is closed except for the inlet and et 19 and 20. .n opening 21 is provided through the partition `16 for living a speaker, which is shown in =FIG. l by the ntom lines as at 22, suspended within the lower cham- 18. More particularly, the opening 21 through the ition is provided for supporting and surrounding the er flared end of the speaker cone such that the back of the cone may be enclosed -by the lower chamber ind the front side of the speaker cone enclosed by the er chamber 17. s previously mentioned, the inlet 19 to lower chamber s a choke which enables loading of the back side of speaker cone by permitting substantially no free air lin the lower chamber `18. As also mentioned previy, this construction is known in the art as the b-ass :x and it is in this sense that the term choke is used. s, with the cross-sectional area of the choke so deed relative to the speaker and volume of the lower nber `18 as to enable the back side of the speaker cone [rive pressurized rather than free air, the speaker is 'ided 'with greater sensitivity. Since this construction :h loads the back side of the speaker cone is known ,ccordance with earlier developments in the art, it l not be elaborated upon. However, by way of exle, I have employed -with a -inch, 50 watt Uniity speaker suspended within a lower 'chamber of 1t fve cubic feet, a choke having a cross-sectional of 40 square inches. lso shown in phantom in FIG. l within lower cham- 18 is an amplifier 23 and suitable electrical controls Although it is conventional practice to place such pment within the enclosure back of the speaker cone, an arrangement is not an essential part of the presnvention. Obviously, the disclosure of the present ntion has not been complicated by a showing of elecl connections 'between the amplifier and the electronetic generator of the speaker. 1e bottom wall 12 of the cabinet is provided with .ers or legs 25 which elevate the bottom wall above floor 15 or other support, thus permitting access to e 19. According to one novel aspect of this inventhe runners are disposed longitudinally of the side i 13 through which outlet openings 20 are provided are further imperforate for a length substantially tensive with such side walls, as shown in FIG. 2, such sound waves emanating from the speaker 22 are ad to travel a distance considerably further than the :est distance between the outlet and inlet. As a reof the above-described arrangement of the upper iber 17, as well as the runners 25 in connection with t openings the enclosure 10` provides a greater kless than the width length of travel for sound waves between the front and back sides of the speaker cone Ithan prior enclosures of comparable size.

Although the runners thus dene a preferred position of the cabinet relative to the support 15, it should be understood, especially in connection with the top, bottom and side wall designations, that the enclosure or cabinet may be laid with either of its side walls 14 or top wall l11 upon the support 1S. With the outlet openings Ztl disposed as shown, it is preferred that the cabinet not be laid upon either of its side walls 13; and, still further,

that it not be disposed with either side wall 13 facing the audience, the reason for which will be more apparent hereinafter. However, if, for example, the outlet from upper chamber 17 consisted of one or more openings through top wall 11, there would be still further flexibility as to the position in which the speaker enclosure may be mounted. Although the foregoing is merely exemplary, it is obvious that the enclosure of the present invention is not restricted by building or room acoustics.

The area of outlet 20 from the upper chamber 17 is of such size as not to choke the sound waves emanating from the front of the speaker, but at the same time has a loading effect upon the front of the cone and thereby further increases its sensitivity. Also, with the outlet comprising openings 20` through opposite side walls 13, there is a spreading of the sound waves emanating from the speaker 22. Thus, with both outlets 20 exposed, and preferably facing transversely to the audience, there results a stereophonic effect which has heretofore been possible only with the use of two or more particularly located speakers. As will be understood hereinafter, this arrangement of outlet openings further enables the use of the improved tremulant type rotor `blade of this invention.

The upper and lower chambers of the cabinet are connected by a passageway 26 which surrounds opening 21 at its lower end and is gradually convergent toward its upper end for elongating the pattern of sound waves emanating from the speaker 22. It will be understood that the sound waves at the flared end of the speaker conc which enter the passageway 26 correspond to the cross section of the speaker in that they have a substantially circular pattern. The bass tones or the pattern of low frequency sound waves at the periphery of the cone are flattened out or elongated by means of the converging passageway 26 such that it has been found possible to reproduce with the enclosure of this invention the full bass range of a pipe organ.

Thus, it can be seen from the drawings, that the width of opening 27 through the upper end of passageway 26 is of opening 21 in a corresponding direction of the flared end of the speaker cone. The desired result, as indicated above, is to flatten out rather than choke the sound. In other words, the circular pattern of the sound waves is transformed into an oval pattern.

In this respect, it is the width of the opening 27 through the upper end of passageway 26 which is critical inasmuch as, on the one hand, too large a width will permit free air and, on the other hand, too narrow a width will tend to Inutile the sound such that many of the intermediate sound waves will not Ibe audible. The length of the opening 27-i.e., in this instance the distance between side walls 14-is critical in that it should be at least long enough to accommodate the elongation of the sound waves in accordance with the narrowing of the width of the passageway or, in other words, its convergency. The critical width of the upper end of passageway 26 depends on a number of variables which Iwill enable one skilled in the art to dimension the passageway to his own needs upon an experimental basis.

h That is, there are several factors which will determine ]ust how much the sound waves can be flattened out and still be audible. Such variables are the variation in lvoice coil diameters of ythe speaker, the variation in speaker cone iiexibility, and the variation in wattage output of the speaker. With the speaker, lower chamber, and choke previously mentioned, I have successfully reproduced the full bass range of a pipe organ with a passageway having a width at its lower end corresponding approximately to the speaker diameter and at its upper `end of approximately inches, `and a length of approximately inches.

To myknowledge, this phenomenon of sound wave pattern elongation has not heretofore been put to practical use in the construction of speaker enclosures. As noted above, its application in the present invention is to reproduce bass tones or low frequency sound waves. In this sense, the bass tones are those generally having frequencies less than 250 cycles.

Referring now Ato the construction of passageway 26 it can be seen from the drawings that it is delined by two spaced apart and laterally extending inner walls 23. These walls extend between side walls 14 so as to define an elongated opening through the passageway extending in substantially lthe same direction as the side walls 13 through-which outlet openings 20 are provided. Substantially horizontally disposed inner walls 29* are connected between side walls 13 beneath outlet openings 20 and the upper end of inner walls 28 so yas to partition olf spaces 30 in the upper chamber at each side `of the passageway 26. These spaces may be left empty or may be filled with any suitable insulating material.

It will be understood that the above-described construction of passageway 26 is preferred principally because of its simplicity and minimum parts, although equivalent structures may be used. As can be seen from FlG. 1, the lower ends of inner walls 28 are disposed on opposite sides of the cone receiving opening 21 and are convergent upwardly therefrom to the open upper end 2.7 through the passageway. l

For illustrative purposes, there is shown in phantom in FIG. 1 a second speaker 31 within the passageway 26 above the speaker 22. This speaker 31 may be of the type used for high frequency sound waves, particularly those above 2,000 cycles, and is thus positioned substan- 1 tially coaxially of opening Z1 and speaker 22 inasmuch as these high frequency sound waves follow substantially straight paths.

The blade for simulating organ music is indicated in its entirety by the numeral 32 in each of FIGS. 1, 2 and 3, and would be incorporated into only those enclosures used for this purpose. As can be seen from the drawings, this blade is mounted in the upper chamber for rotation above the opening from which the speaker 22K is suspended and about an axis extending substantially longitudinally of the side walls 13 through which outlet openings 20 are provided. in this manner, assuming a rotation of the blade in a single directional sense, sound waves emanating from the front of the speaker ZZ will be Adirected or diverted from one opening 2.0 and then to the other and, intermediate such diversions, the sound waves, rather than being muiiied `as in prior `art structures, are spread between passageto each of said outlet openings,

It is thus important that the blade be mounted about an axis above the opening or, -in the preferred form of the invention shown in the drawings, also above the outlet 27 through Ithe open upper end of passageway 26. In this rnanner, with the blade 32 disposed in one angular position as shown in FlG, l the sound waves from passageway 26 are diverted into the outlet opening 2()l in the left side Wall 13 of the cabinet as it is shown in FIG. l. However, `as the blade is further rotated such that it reaches a substantially horizontal position, there will be no mufiling or `choking of the sound waves, but to the contrary, they will be permittedV to pass outwardly through either of the outlet openings 20. Also, as shown in FIG. l, the lower end of the blade 32 is so mounted as to be spaced a short distance from one edge or side opening 27 as it diverts sound waves to the outlet opening neare the opposite side.

it is further important that the blade extend lengt] wise substantially coextensively with the length of tl opening 27 through the upper end of the passageway 2 and that it be of a width greater than that of the uppt end of such passageway. In this manner, the axis n rotation of the blade may be disposed a distance less the one-half of its width above the upper end of the pa sageway so that, in reaching `a position such as is show in FIG. 1, substantially `all of the .sound waves emanatir from speaker 22 yand passing outwardly through pass/ag` way 26 `are diverted in a single direction and through single outlet opening. Obviously, non of the afor mentioned advantages and functions of the blade 32 ai possible with the previously described tremulant roto of the prior art,

As mentioned above, it is preferred that the blade E be employed in connection with the sound wave pattex elongating passage 26 although, as will be understoo the blade may be used solely in connection with tl speaker opening 21 in which case the relation of tl blade to such speaker opening would preferably co respond to the above-described relation of the bla( to the opening 27 through the upper end of passagewz 26. Also, of course, it is the disposal of outlet ope: ings 20 through opposite side walls 13 which makes po sible the improved functioning of the blade 32 in simi lating organ music.

Referring more specifically to Athe drawings, it cz be seen that the blade itself is provided with stub shaf 33 supported in bearings 34 at opposite ends at the si( walls 14. The blade is rotated by means of a pulley E on one of the stub shafts and carrying a belt 36 whit is driven by any suitable motor 37. As shown in tl drawings, one of the substantially horizontally dispose inner walls 29 provides a .support for the motor 37.

In `a preferred construction of the enclosure, the t( wall 11 is disposed at a level relatively close to the upp end of the blade 32 when it is vertically disposed su( that leakage facrossthe top of the blade in such vertic position will be kept to a minimum. The speed at whit the blade will be rotated is determined, of course, l the simulated eifect it is desired to obtain.

From the foregoing it will be seen ythat this inventif is one well adapted to attain all of the ends and objec hereinabove set forth, together with other advantagwhich are obvious and which are inherent to the aj paratus.

It will be understood that certain features `and su combinations are of utility and may be employed wit' out reference to other features and subcombination This is contemplated by and is within the scope of tl claims.

As many possible embodiments may be made of tl invention without ydeparting from the scope thereof, it to be understood that Iall matter herein set forth or shou in the accompanying drawings is to be interpreted as lustrative and not in la limiting sense.

The invention having been described, what is claimt l. An acoustical enclosure [for] with a Ispeaker ha ing a speaker Cone, comprising a cabinet having an i1'. perforate top, a bottom and side walls Iand a partiti( extending between the side walls to Idivide the cabin into upper and lower chambers, said cabinet being closr except for an outlet from the upper chamber and an i let to the lower chamber which comprises a chol through the fbottom wall, the partition lbeing provid: with an opening for receiving [a] the speaker cone su pended within the lower chamber above the choke, tl outlet from upper chamber comprising outlet ope ings through opposite side walls of the cabinet of a si;

.K to produce a loading effect upon the front of the speak ich the outlet openings are provided and at opposite through two opposite side walls thereof, the top wall :s of the choke, said runners being imperforate for being imperforate, [and an inlet to the lower chamber gthening the travel of sound `waves between each f comprising a choke through the bottom wall thereor",] outlet openings and choke. the partition provided with an opening for receiving [a] i. An acoustical enclosure [for] with a speaker havthe speaker cone suspended within the lower chamber, a speaker cone, comprising a cabinet having upper said cabinet comprising bayjle means ai the rear of the l lower chambers and being closed except for 1an outspeaker for minimizing the cancellation of energy from from the upper chamber and an inlet to the lower the speaker, and a blade mounted in the upper chamber .mber which comprises a choke through the bottom for rotation above said opening about an axis extending 1 thereof, a passageway in the upper chamber and 10 in the direction Iof the side walls through which the outrnected to the lower chamber [connecting the upper let openings are provided, and substantially parallel to l 4lower chambersl `and means at the lower end of the plane of the partition. passageway having a substantially circular opening 7. An acoustical enclosure [for] with a speaker having t'ethrough for receiving [a] the speaker cone suspenda speaker cone and month, comprising a cabinet having within the lower chamber, said passageway surroundupper and lower chambers closed except for an outlet the substantially circular opening through the speaker from the upper chamber comprising openings through te receiving means at its lower end and being gradtwo opposite side walls thereof, the top wall being imly convergent upwardly to an elongate portion at its perforate, Eend an inlet to the lower chamber compriser end connecting with the upper chamber, the area ing a choke through the bottom wall thereoi,] a passagesaid elongate portion being substantially that of the way in the upper Chamber and connected to the lower stantially circular opening through the speaker cone Chamber [connecting the upper and lower chambTSl, giving means for transforming the sound `Waves means at the lower end of the passageway for receiving anating from the cone from a circular to an oval [a] the Speaker 0011 Suspended Within the lower chamiern y (ber, said cabinet comprising bajle means enclosing the Sound reproduction apparatus, comprising a cabinet real' 0f h'e Spee/eel OI minimizing the Cancellation 0f ing top, bottom and side walls, a partition extending energy imm the Speel/Cer, and a 5blade mounted in the Ween the side walls to divida the cabinet into upper upper chamberabove the Upper end of the passageway l lower chambers, said partition having an Opening, fOl rotation abOllt Em aXS eXtendIlg in the dlreClOn Of l cabinet being closed except for having an outlet The Side Walls tllfOUgh Which the Ollllll Openings afln the upper chamber and an inlet to the lower cham- PTOVded, and Parallel l0 The "10m/1 0f fhe Speel/fel" which comprises a choke through the hmmm Wah7 a 8. An acoustical enclosure of the character defined in akr con@ received through [an] mid Opening in the claim 7, wherein the 'bla-de extends lengthwise substantition for sus-pension within the lower @bambi-,1fy and t1ally from side wall to side wall of the cabinet and is assageway in the upper chamber having a substantially 0f a Width 'greater than that 0f the UPPEI @11d 0f the :ular portion at its lower end in surrounding relation passageway, and the aXS Of rotation of the blade is dis- Lhe partition opening and communicating through its posed a dlstallce leSS than 011B half of its Width above Ier end with the outlet, said passageway being gradu- Sad UPPeT end 0f the passagewayconvergent from said substantially circular portion An acoustical enclosure of the character dened in its lower to a substantially elongate portion at its C1mm 7, Whereln the passageway is gradually convergent ,er end5 the area of Said elongate portion [being sub 40 from a substantially circular portion at its lower end surltiauy that of the Outlet from the Speaker come for roundmgsaid speaker cone receiving means to an elonlsforming the sound waves emanating from the cone gate POrtlcm a? lts upper end for lfansfofmlng the SOUIld n a circular to an Oval pattern' waves emanating from the speaker cone `from a circular Sound reproduction apparatus of the character det0 an [Ovel] Oval Patternd in claim 3, wherein the outlet from the upper chamv comprises an opening -through a side wall thereof, References Cited in the le of this patent top `wall being imperforate, and the upper portion or the original patent the passageway being elongated in a direction of the a wall through which the outlet opening is provided. UNITED STATES PATENTS An acoustical enclosure [for] with a speaker having FOREIGN PATENTS 7eaker cone, comprising a cabinet having top, bottom 541668 Great Britain Aug. 16, 1950 side walls and a [partion] partition extending been the side walls to divide the cabinet into upper and OTHER REFERENCES 'er chambers, said cabinet being closed except for Publication: The Karlson Enclosure, by Karlson Asoutlet from the upper chamber comprising openings sociates, Inc. (page 30is most pertinent). 

